This invention relates to a large-scale integrated circuit (hereinbelow, termed "LSI") chip which includes superconductive devices. In particular, this invention relates to devices having Josephson junction (hereinbelow, termed "Josephson device").
In the past, in LSI chip including Josephson devices, experiments on the delay time have been performed (e.g. see H. C. Jones, D. J. Herrel, "The Characteristics of Chip-to-Chip Signal Propagation in a Package Suitable for Superconducting Circuits", IBM Journal of Research and Development, Volume 24, Number 2, pages 172-177, March 1980). As shown in FIG. 1, the LSI chip used in this prior experiment was provided with a drain connector 10 on one side (e.g., the left side) of the chip 1 and a source connector 12 on another side (e.g., the upper side). Both of the connectors are connected by a superconductive line 11 which is disposed within the chip. An external input signal is applied to the superconductive line 11 through the drain connector 10, and an output is delivered from the source connector 12.
Frequently, in such an arrangement as shown in FIG. 1, the input signal is affected by noise on a transmission line outside the LSI chip. Accordingly, when the superconductive line 11 to which the input signal is applied in long, circuitry within the LSI chip is liable to experience adverse effects. Therefore, the superconductive line 11 needs to be shortened. When, as in the LSI chip 1 of the aforementioned experiment, the superconductive line is laid from one side to another side of the LSI chip, such a superconductive line can be shortened only at the four corners of the chip 1. Unfortunately, this poses a problem in the layout. In the presence of five or more pairs of source connectors and drain connectors, generally one or more superconductive lines cannot be shortened. In addition, it becomes difficult to design the layout so that the output line of an input buffer which is magnetically coupled with the superconductive line does not intersect with this superconductive line.